Flow sensitive directional control valve



July 25, 1961 J. ROBINSON ETAL 2,

FLOW SENSITIVE DIRECTIONAL CONTROL VALVE Original Filed D80. 6, 1954 2 Sheets-Sheet l INVENTORS 20 JAMES ROBINSON I KENNETH COURT July 25, 1961 J. ROBINSON EIAL 2,993,500

FLov'v SENSITIVE DIRECTIONAL CONTROL VALVE Original Filed Dec. 6, 1954 2 Sheets-Sheet 2 IS IS E 62 77 I64 54 2 82 8 86 20 2o 0 I58 l O r I 17s 7 198 85 769w? g g- 0 FIG. 2

INVHVTORS JAMES ROBINSON KENNETH COU T United States Patent 2,993,500 FLOW SENSITIVE EIRECTIONAL CONTROL This invention relates to power transmissions, and is particularly applicable to those of the type compnsmg two or more fluid pressure energy translating devices, one of which may function as a pump and another as a fluid motor.

The present application constitutes a dlVlSlOIl of the co-pending application of James Robinson and Kenneth Court filed under Serial No. 473,418 on December 6, 1954, now Patent No. 2,918,902, in which the flow sensitive directional control valve is disclosed as incorporated in a motor regulating system.

The invention particularly pertains to hydraulic transmission systems of the type incorporating a double acting cylinder for actuating a load device wherein the length of stroke of the main piston may be remotely adjusted and controlled. Systems of this type have been particularly useful for operating the trailing agricultural implement of a towing tractor, such as a plow. The operator of such a system may from the tractor seat not only control the directional operation of the main piston of the cylinder for raising and lowering the implement but may also adjust from the tractor seat a device or member for limiting the stroke of the main piston.

One such form of stroke adjusting device is an auxiliary hydraulically actuated stop piston which may be thatably mounted in the double acting cylinder. Although a separate source of pressure fluid may be utilized to operate the auxiliary piston it may be operated together with. the main piston of the cylinder from a single source of pressure fluid such as a fluid pump driven from the power take-off of the tractor.

It has been the practice to utilize in such systems one manually operated directional control valve for controlling the operation of the main piston and another manually operated valve for controlling the adjustment of the auxiliary stroke limiting device or member. Although the directional control valves and the pump may be conveniently mounted in a block or casting to form a power-pack it is necessary for the operator of the system to focus his attention on and to manipulate either one of two directional control valve handles.

It is therefore an object of this invention to provide an improved hydraulic transmission system for remotely controlling the directional operation and stroke adjustment of a double acting hydraulic cylinder or motor for driving a load device.

It is another object of this invention to provide a hydraulic system incorporating a fluid cylinder or motor for driving a load device in which both the directional operation of the motor and the stroke length of the main piston is controlled and adjusted by a single directional control valve having one manually operated control handle for both directional and stroke adjustment operations of the motor.

It is anotherobject of this invention to provide .in a transmission of the type recited an automatically operated valve coacting with a manually operating directional control valve which is sensitive to low flow conditions in one position of the directional control valve to cause adjustment of the motor stroke limiting device or element and which under high flow conditions in another position of the directional control valve is operative to permit actuation of the motor in the conventional manner for driving the load device.

It is still another object of this invention to provide a hydraulic power transmission of the type and for the purposes recited wherein an actuator and stroke limiting member for the actuator mounted at one station may both be controlled and operated from a remote station at which is located a pressure fluid source and single manually operated control, with the two stations interconnected by only two, dual function, supply and return conduits.

It is a further object of this invention to provide a directional control valve of novel construction which is sensitive to flow conditions to port fluid to desired locations or elements of a hydraulic system, such as to the main piston or to an auxiliary stroke limiting piston of a double acting cylinder.

It is still another object of this invention to provide a hydraulic power transmission system of the type and for the purposes recited which is relatively simpler and more economical and efiicient in construction and operation, which reduces the number of manually operated controls and plumbing lines, and which is more convenient and simpler for the operator of the system.

FIGURE 1 is a diagrammatic view of a hydraulic power transmission system embodying a preferred form of the present invention.

FIGURE 2 is a sectional view of a directional control valve incorporated in the power transmission system illustrated in FIGURE 1.

Referring to FIGURE 1 there is shown a hydraulic power transmission system adapted for actuating and remotely controlling the operation of a load device, for example, a trailing agricultural implement of a tractor, such as a plow. The hydraulic system includes a pressure fluid source comprising a fluid pump 10 supplied with fluid from a tank 12, a fluid motor 14 for driving the load device, not shown, and interconnected with the pressure fluid source and the motor a combined directional and flow control valve 16 and a flow sensitive directional control valve 18. The pump 10 is adapted to be driven by a prime mover, not shown, such as the power takeofi of a tractor.

The pressure fluid source and directional control valve are mounted at one station which is indicated in block form and by the numeral 19, such as the tractor, while the motor including a hydraulically adjustable stop member, and a flow sensitive valve are mounted at a remote station which is also indicated in block form by the numeral 21, such as the trailing implement of a tractor. The arrangement is such that only two conduits are necessary for interconnecting the stations and for controlling at one station both the motor and motor stop member remotely located at the other station.

The inlet 20 of the pump 10 is connected to the tank 12 by a supply conduit 22 while the outlet 24 thereof is connected by a pressure delivery conduit 26 to a pressure inlet port 28 of the control valve 16. A pressure relief valve 30 is incorporated in the pressure delivery conduit 26 to regulate the maximum pressure of the system in the conventional manner and exhausts excessive pressure fluid to the tank 12 :by means of a conduit 32.

The motor 14 for driving the load device is of the type'comprising a cylinder 34 having shiftably mounted therein a fluid operated main piston 36 and 'an auxiliary piston 38 the latter of which may be hydraulically adjusted and locked to limit the stroke of the main piston in one direction. A piston rod 40 associated with-the .main piston 36 extends from one end of the cylinderfor indicated by the numerals 46 and 48, is mounted at one end in a closure member 50 of the cylinder and extends into a hollow section 52 of the main piston and rod. The auxiliary piston 38 is fioatably mounted onthe tubular member 42. The circumference of the tubular member 42 in relation to the area of the hollow section 52 of the main piston and rod is adapted to provide a passage within the rod and main piston around the periphery of the tubular member which is indicated by the numeral 54.

Three expansible chambers are formed within the cylinder one of which is located between the inner face of the cylinder closure member 50 and the auxiliary piston 38 which is indicated by the numeral 56. Another chamber, indicated by the numeral 58, is formed between the opposite face of the auxiliary piston 38 and the adjacent face of the main piston 36. The remaining expansible chamber 60 is formed between the opposite face of the main piston 36 and the inner face of a closure member 62 at the rod end of the cylinder. The cylinder 34 is provided with a motor port 64 at the rod end of the cylinder which leads to the main piston chamber 60 and a motor port 66 is located in the opposite end of the cylinder leading to the chamber 56. The chamber 58 is connected to the opening 46 of the tubular member 42 by means of the passage 54 surrounding the outer periphery of the tubular member 42 within the hollow section 52 of the piston 36 and rod' 40, and the opening 48 and the passage 44 of the tubular member 42.

The present invention utilizes one manually operated directional control valve 16 to control the operation of both pistons with the cooperation of the automatically operated flow sensitive directional control valve 18. Valve 16 may be of the well-known type disclosed in the patent to Kirkham, No. 2,448,532, or of the type disclosed in the patent to Stephens, No. 2,448,557, which type of valve is shown schematically in FIGURE 1 and is shown in detail in FIGURE 2. The valve will be described first as shown schematically in FIGURE 1 and will subsequently be descn'bed in more detail as disclosed in FIGURE 2. The control valve 16 is in essence'a four-way directional valve which in addition to the pressure port 28 is provided with a tank return 7 operable by a control handle indicated by the numeral 71. In the neutral position of the handle shown, 'indicated by the letter N, the pressure port 28 is connected to the tank port 6 8for unloading the pump 10 while the motor ports 69 and 70 are blocked from communication with each other and the pressure and tank ports. In the position of the lever arm indicated by Rl and R-Z the pressure port 28 is connected to the motor port 78 while the motor port 69 is connected to the tank port 68. In the position of the lever: arm indicated by Ll and L-Z the pressure port 28 is connected to the motor port 69 and the motor port 70 is connected to the tank port 68.

- The directional control valve 16 is of the type which when thelever arm" is in either of the positions R-l or 1L1 will only be partially open so as to restrict the flow of fluid1therethrough and thereby direct less than full 1 pumpdisplacement to the motor or to the flow sensitive valve 18. Fluid from the pump in excess of the restricted quantitywillbe exhausted to tank 12 through the relief valve 30. When the control handle 71 is shifted to-either tion of motor operation as a pressure delivery inlet port and in the opposite direction of motor operation as a motor return port. The conduits 72 and 76 may have incorporated therein flexible hoses, as shown, 'when for example the transmission is utilized to operate a trailing implement of a tractor. The tank port 68' is connected to the tank 12 by a return conduit 77 leading to the conduit 32. v

The directional control valve 16. incorporates a spool or piston for controlling intercommunication between the ports which remains in the position operated to until displacement from the motor ceases. In control valves of this type a restriction or valve of the back pressure type may be placed in the valve body passages which return fluid from the motor to build up a pressure on either one of two pressure responsive end surfacesof the valve spool suflicient to overcome the resistance of a centering spring which returns the valve spool to a neutral position when motor displacement ceases.

For the purposes of convenience the pressure responsive end surfaces of the valve spool indicated by the numerals 79 and 81 and the valve circuit for the surfaces have been shown in FIGURE 1 externally of the valve body. A valve passage 83 which is adapted to connect the conduit 72 to the conduit 77 when the valve spool is shifted rightwardly is connected to the end surface 79 by a passage 85. A restriction 87 is placed in the passage 83 to create a pressure on the end surface 79 when motor displacement is conducted from the conduit 72 to 77 sulficient to maintain the valve spool in the rightward operating position. A passage 89 adapted to connect the motor conduit 76 to the tank conduit 77 whenthe' valve spool is shifted leftwardly is connected to the. other end surface .81 of the valve spool by a passage 91. A restriction 93 is placed in the passage 89 and creates a pressure on the end surface 81 when motor displacement is conducted from the motor conduit 76 to the tank conduit 77 sufiicient to maintain the valve spool in the leftward operating position. When motor displacement ceases the pressure in either. of the lines 8501' 91 decreases to permit the valve spool to be automatically operated by the centering spring to the neutral position.

Referring now to FIGURE 2, valve 16 is composed of a body 152 having a longitudinal bore 154 extending completely therethrou-gh which is closed at opposite ends thereof. Shiftably mounted within the longitudinal bore 154 is a valve spoolindicated by the numeral 156 which has a portion 158 extending from the boreoutside the body and which may have a lever thereon 7.1 as indicated inFIGURE 1. V

The body 152 is provided with a pressure port 28 which opens to a pressure chamber160 connected by branches 162 and 164 to the longitudinal bore 154.- The external tank connection port 68 leads to the return pass-age 77 (shown exteriorly of the valve shown in FIGURE 1). The return passage 77 is directly connected to a centrally located valve bore tank port 166.

The spool 156 has a center land 168 which in the position of the valve spool shown in FIGURE 2'connects the 'of the positions R-2 or fL-Z the directional valve will be in the wid'e'open position to directfull pump displacethe cylinder motor port 64 by a conduit '72 and the remainpressure'tchamber 160 and its branches 162 and 2164 to the tank port 166 so as to form a direct pump unloading connection in the neutral position of the valve shown from '174, and lands 176 and 178 to' the left and right respectively of center land.168 cooperate. with the-center land 168 to disconnect the branches 162 or '164 f'rom the en- .larged tank port 166. When, shifted to' the' lefg a transverse valve spool port 180 cracks over a valve-bore motor .ing motor port of the control valve-16 is connected to -an.external connection port 74 of the flow sensitive valve port 182. :Ihe pressure branch 162 is then connected by a valve spool transverse port 184 to-ia'hollow sect-ion! of the valve spool. 1-

A check valve 188 biased to the position shown by a spring 190 is mounted in the hollow section 186, which check valve is opened by pump flow which is their free to flow from the valve spool port 180 to the valve bore motor port 182 and thence to the external connection motor port 69. When the valve spool 156 is shifted rightwardly, the center land 168 in cooperation with its immediately adjoining land 178 cuts ofi the valve bore tank port 166 from the pressure port by crossing over into the sealing area 174, and the pressure branch 164 is connected by means of a valve spool transverse port 192 to a hollow section 194 in the right end of the valve spool.

A check valve 196 is mounted in the hollow section 194 and is biased to the position shown by a spring 198. Pressure fluid from the pressure branch 164 enters the hollow section 194 by means of the transverse port 192, shifts the check valve 196 rightwardly and pressure fiuid is conducted by means of a valve spool transverse port 200 in the valve spool to a valve bore motor port 202 which is directly connected to the external connection motor port 70, shown in FIGURE 1.

The valve spool 156 may be shifted partially rightwardly to a position where the valve spool transverse port 200 cracks slightly over the valve bore motor port 202 so as to meter flow to the flow sensitive valve 18. The valve spool 156 may also be shifted further rightwardly so as to completely open the transverse port 200 to valve motor port 202 and thus direct a large flow to the flow sensitive valve 18. Likewise the valve spool 156 may be shifted partially leftwardly to the L-l position whereby the valve spool transverse port 180 is opened slightly to the valve bore motor port 182. Pump flow may thus be metered in said position to the motor cylinder 14. When the valve spool 156 is shifted completely to the left, the valve spool transverse port 180 is open completely to the valve bore motor port 182 and full pump flow is conducted to the motor cylinder 14.

Valve spool 156 is provided with end sections of reduced diameter which provides a left end, pressure effective annular area 79 and a duplicate right end pressure effective area 81, which are shown schematically in FIG- URE 1. When valve spool 156 is shifted leftwardly, fluid returning to the motor port 202 is connected by the right end reduced portion of the valve spool to a valve tank return port 204. From the tank return port 204, return flow is conducted by a passage '91 through a rmtriction 93 to a passage 89 and thence by means of valve bore tank port 166 and passage 77 conducted to the external tank connection port 68. The restriction 93 causes a pressure build-up which acts on the annular spool area 81 and which is suflicient to overcome the spring 170 in order to maintain the valve spool @156 shifted to the leftward operating position. When return flow ceases there no longer is a pressure build-up ahead of the restriction 93 and the spring 170 returns the valve spool 156 to the neutral position. v

When valve spool 156 is shifted rightwardly, fluid returning to motor port 182 is connected by the left end reduced portion of the valve spool to a duplicate tank return port 206. From the tank return port 206, return flow is conducted by a passage 85 through a restriction 87 to a passage 83 and thence by means of valve bore tank port 166 and passage 77 to the external tank connection port 68. The restriction 87 causes a pressure build-up which acts on the left end annular area 79 and is sufficient to overcome the spring 1707to cause the valve spool 156 to remain. shifted to the rightward operating position. When return flow ceases there no longer is a pressure build-up ahead of the restriction 87 and the spring 170 returns the valve spool 156 to the neutral position. I Theflow sensitive valve 18 comprises a body 78 which in addition to the connection port 74 is provided with a motor: pprt,.80 connected to the cylinder port 66 and to ;chamber 56 of motor 14 by a conduit 82 and has a "$991.9 P P8 s nn c d to th amp s P t and to chamber 58 of motor-14 by a conduit 86. The body 78 has a centnally located longitudinal bore 88 closed at one end by an end cover 90 and the opposite open end of which comprises the double function motor inlet and return port 74. The bore 88 is constructed with motor ports 92 and 94 located on opposite sides of an intermediate port 96. The external connection motor ports 80 and 84 of the body are respectively connected to the valve bore motor ports 92 and 94 by passages 98 and 100.

Communication between the several ports is controlled by a flow sensitive piston valve member indicated generally by the numeral 102 which is shiftably mounted in the bore 88 and forming chambers 103 and at opposite ends of the bore. When the pump 10 is connected to the port 74 of valve 18 and the control handle 71 of valve 16 is in the position R-l to restrict flow, the flow sensitive piston valve member 102 remains in the position shown to connect the inlet port 74 to the motor port 80. When the handle 71 of the control valve 16 is in the R-Z position to permit high flow to the inlet port 74 the valve member 102 is shifted leftwardly to block port 74 from motor port 80 and to connect port 74 to motor port 84.

When the desired plowing depth has been reached the main piston 36 of the cylinder 34 will be in abutment with the auxiliary stop piston 38. If it is desired to plow at a slightly greater depth the control handle 71 of valve 16 may be shifted to the L-l position to connect the pump to the left end of motor 14. The valve member 16 restricts flow to the motor in the L-l position and valve member 102 will remain in the position shown to conduct motor displacement from port 80 to the port 74 of valve 18. Whenever the control lever is shifted to the L-2 position the valve member 102 is operated rightwardly because of the high flow conditions created to connect port 84 to port 74 while closing motor port 80 to the port 74.

The valve member 102 has a longitudinal passage 104 extending completely therethrough opening at opposite ends to the chambers 103 and 105 which in the position of the valve shown is connected to the intermediate port 96 of the bore 88 by means of spaced apart transverse ports 106 and 108 opening to the port 96 and connected to the motor port 92 of the bore 88 by a transverse port 110. A restriction to large flow from or to the port 74, indicated by the numeral 112, is located in the longitudinal passage 104 adjacent the transverse port 108. A venting check valve assembly is mounted in the passage 104 comprising a poppet 114 biased by a spring 116 on a seat-118 formed in the passage 104. A spring 120 having a resistance greater than the resistance of spring 116 and mounted between snap rings 122 and 1-24 respectively abutting shoulders 126land 128 of the valve member 102 biases the valve member 102 to theneutral position shown. 'The valve member 102 is constructed with substantially balanced pressure responsive end areas indicated generally by the numerals 130 and 132, which are respectively exposed to the pressures existent in the chambers 103 and 105. v

In the centered position of the valve member 102 shown, low inlet flow to the port 74 is blocked from communication with the port94 and the passage 100 by a right end land 134 of the valve member. A land 136 between" the transverse ports 106 and 108 permits flow from the passage 104 to the valve motor, port 96 by the medium of the transverse port-108 and from the .motor port 96 to the passage 104 through the medium of transverse-port 106. A land138 located between land 134 and-land 136 blocks the passage100 from trans- -verse port 108 and intermediate port 96;. I T

When high inlet flow is conducted to'the bore 88 from the inlet Jpo'rt74 a'pressure increase ahead of the restric- 102 sufiicient to overcome the resistance of the spring 120 for operatingthe valve member 102 leftwardlyand land 134 .opens communication between the inlet port 74; chamber 103' and the'passagel100leading to motor port 84.

When-the valve member 102 is operated in the opposite direction under the influence of high flow directed to' the bore motor port 92 from motor port 80 and sensed by the restriction 112, the transverse port 108 is no longer in communication with the intermediate port 96 butwith passage 100 and motor port 94. Displacement from thevcharnber 58 of the motor 14 is conducted from the passage 100 to the port74, now acting as a return .port, by a branched'passage 140 having a seat opening 142 leading to the chamber 103 which is controlled by apoppet valve 144 biased to the closed position upon the seat 142'by a spring 146. With the valve member 102 *shi-fted rightwardly the spring 146 of the poppet Jvalve144, the resistance .ofwhich is greater than that of the spring 120, is adapted to buildup a pressure at the left end of the valve'mernber 102in chamber 105 sufficient to maintain the valve in the rightward operating position until the displacement from the motor ceases.

Pressure on the right end area of valve 102 will be low because port 74 is connected to tank during this operation. With transverse port 108 connected to motor port 84 the pressure existent ahead of poppet valve 144 is transmitted by means of passage 100, transverse port 108andlongitudinal'passage 104 to act against the venting valve 114 and tending to maintain the valve seated. A substantially equal pressure suflicient to, maintain the valve shifted rightwardly against the urging of spring 120 is transmitted from chamber 56 of motor 14 to the left end surface 132 of .valve 102 by means of, conduit 82, motor port 80, passage 98, transverse port 110 and longitudinal passage 104. This pressure is also transmitted by the passage 104 to the opposite side of vent valve 114 to equalize the pressures thereon and the spring 118 will maintain the valve seated.

Rightward movement of the valve member 102 is limited by a shoulder 147 located on one side of the transverse port 110 coming into abutment with the snap ring 122 while leftward movement of the valve member is limited by a shoulder 1'49 located on the opposite side ofthe transverse port 110 coming into abutment with the snap ring 124.

A restriction 151 forming a. portion of longitudinal passage 104 is located between the transverse ports 106 and 108. When the main piston of the motor is operated in abutment with the auxiliary piston the restriction 151 prevents free venting of fluid from chamber '56 of the motor. through the venting valve 114 and thus prevents' continued movement of the auxiliary piston which shifts slightly when the mainpiston comes into abutment therewith under high flow conditions. .With continued displacementfrom the motor 14 the main valve 16 would not be operated to the neutral position and the main 7 piston would continue to shift the auxiliary piston. The

restriction 151 thus aids in'insuring operation-of the main directional control valve 16 to the neutral position .when the main motor piston. has reached the limit of its of motor 14 and as the valve-102 shifts leftwardly the fluid displaced from the left end of valve 102 is also conducted to the chamber 56. The auxiliary piston 38 is thus shifted slightly together with the main piston-36 before the main piston shifts alone. As will be subsequently explained, when the main piston isshifted rightwardly to lower the plow the auxiliary piston also shifts slightly so that the system is self-correcting in returning and maintaining the auxiliary piston to the adjusted position.

High flow conducted to the inlet port 74 and chamber 103 of the valve 18 must flow through restriction 112 and a pressure increase immediately takes place ahead of the restriction to create a pressure differential in the chambers 103 and on the end areas 130 and 132 of the valve member 102 sufiicient to overcome the resistance of the spring and to operate the valve 102 leftwardly until the shoulder 149 comes into abutment with snap ring 124. Land 134 of valve member 102 which. formerly blocked port 74 from communication with motor port 84 now permits communication between saidports and fluid is conducted by conduit 86 to the tubular opening 46 of motor 14 and by means of tubular passage 44 and of piston rod passage54' to motor chamber 58.

With the valve member 102 shifted leftwardly chamber 56 of the motor is blocked from the intermediate valve port 96 asthe transverse port 106 has passed out of communication with the port 96. The main motor piston 36 will be actuated speedily leftwardly to raise the plow until it comes to the limit of its leftward stroke at which time flow from the motor chamber 60 which had been conducted to tank 12 by conduit 72, across the ports 69 and 68 of valve 16 to the conduits 77 and 32 ceases. During motor operation pressure increases take place in the passage 83 ahead of the restriction 87 in the valve 16 which conducts fluid from the motor. The pressure increases are transmitted by passage 85 to the end' operating surface 79 of the valve spool to maintain the valve in the K2 position. When flow from the motor ceases the pressure decreases at the valve spool endsurface 79 and the valve spool is automatically operated to the N or neutral motor stop position.

' The valve member 102remains in the position operated to until the valve handle 71 is shifted from the N position to the ls-2 position at which time port '74 of valve 18 is connected to tank 12 by the directional valve 16 and the trapped pressure in chamber 103 on the right end surface of the valve member 102 is released. High flow from the pump 10 is directed across the ports 28 and 69 of directional valve 16 to chamber 60 of motor 14 and the main piston 36 of the motor is actuated speedily rightwardly to lower the plow. The 'spring'120 of valve member 102 initiates movement of the valve member 102 to the centered position and with high flow directed to chamber 60 of the motor 14 against the main piston of the motor, the auxiliary piston 38 is shifted slightly to displace fluid from the chamber 56 to the motor port 80 of valve 18 and thence by passage 98 and transverse port 1100f the valve member 102 to the longitudinal passage 104. Because of the high flow tending'to pass through themain restriction 112 of the valve a pressure'difierential is created on the opposite ends 130 and 132 of the valve member 102 to desired plowing depths, if thecontrol handle-71 of dire'ctional valve-16-is manually shifted to the lb-2, position highfiow from the pump 10 will be conducted to the. inlet port '74 of flow sensitive valve 18. from the pump 10 is conducted'to port 74 of valve 18 by conoperate the same rightwardly from the neutralposition until the shoulder 147 of "the valve member comes into abutment with the snap ring 122. The transverse'port 108 of the valve, member passes out of communication with intermediate valve bore port-96 and the land 136 blocks communication between the valvebore motor port 94 and the intermediate port 96. The motor port 80 position to limit the rightward stroke'of themain piston '36.-- Fluid f-ro'nrthe pump 10 is conducted to the cham- 9 her 60 of the motor 14 to actuate the piston 36 righ wardly until the piston 36 comes into abutment with the auxiliary piston 38. Displacement from the chamber- 58 of the motor is conducted by means of the piston rod passage 54, tubular opening 48 and the passage 44 to the tubular opening 46 whence by means of conduit 86 it is conducted to the motor port 84 of valve 18. From the port 84 motor displacement is conducted by valve passages 100 and 140 to the poppet valve 144 which is operated to open the seat 142 from whence fluid is conducted to the chamber 103 and port 74. As transverse port 108 is connected to the passage 100 a divided flow may take place but the restriction 112 together with the resistance of valve spring 146 maintains sufficient valve operating back pressure. From the port 74 fluid displacement is conducted by conduit 76 and across the ports 70 and 68 of directional valve 16 to the conduits 77 and 32 and thence to tank 12.

Fluid returning from motor 14 in the passage 89 of the valve 16 must pass through the restriction 93 causing a prmsure increase ahead of the restriction which is transmitted by passage 91 to the right end operating surface 81 of the valve spool to maintain the directional valve 16 in the L-Z position. When the main piston 36 of the motor 14 comes into abutment with the auxiliary piston 38 the piston 38 is shifted slightly and the slight amount of fluid displaced from the chamber 56 is extruded through the vent valve 114 of valve member 102. This flow is dampened by the restriction 151 and with cessation of motor displacement the pressure decreases at the right end operating surface 81 of the main directional valve spool causing the valve 16 to be automatically operated to the N or neutral motor stop position. As

tank pressure had been existent at the right end operating surface 130 of valve member 102 the spring 120 will return the valve member 102 to the centered position. Fluid displaced from valve chamber 105 as the valve 102 shifts leftwardly to the centered position is conducted through the passage 104 and the vent valve 114, the spring 5 resistance of which is less than the operating force of the spring 120, to the right end chamber 103 of the valve.

If it is desired to plow at a slightly greater depth the control handle 71 of the directional valve 16 may be shifted to the L1 position and a low-volume of fluid will be conducted to the chamber 60 of the motor to actuate the main piston 36 which will shift the auxiliary piston. Fluid will be displaced from the motor chamber 56 to the motor port 80 from whence it is conducted by the passage 98 to the valve bore motor port 92 and by transverse port 110, passage 104, transverse port 106, motor port 96, transverse port 108 back to the passage 104 and through the restriction 112 to' chamber 103 and thence to port 74 from where it isconducted to the tank 12. The restriction 112 does not offer aresistance to low flowsoth at'theflow' sensitive valve member 102 remains in the centered position. The operator of the system, when the required plowing depth has been reached, will manually return the control valve handle 71 to the N motor stop position.

If it is desired to raise the plow slightly the control handle 70 may be shifted to the R-l position. Low flow is conducted to the port 74 of flow sensitive valve 18 from whence it is conducted by the chamber 103, passage 104 through the restriction 112, and around the motor port 96 to the passage 104 by means of the transverse ports 108 and 106, and thence by the transverse port 110, passage 98, motor port 80 and conduit 82 to the chamber 56 of motor 14. The auxiliary piston 38 is operated to also shift the main piston 36 and displacement from the motor chamber 60 is conducted by conduit 72 to the directional control valve 16 and thence to tank 12. The control handle 71 may be shifted to the N motor stop position when the required adjustment has been made.

Thus, when the auxiliary piston 38 has been adjusted to a selected position the plow may be raised rapidly by shifting the control handle 71 of valve 16 to the R2" position. High flow to the inlet port 74 of valve 18 causes the flow sensitive 'valve 102 to be operated and port fluid to chamber 58 of the motor to shift the main piston leftwardly. Upon completion of the motor stroke the directional valve handle 71 returns automatically to the neutral position. To lower the plow rapidly back to the preceding plowing depth position the control handle of valve 16 is shifted to the L-2 position and temporary high flow from the motor chamber 56 is directed to the motor port of the flow sensitive valve 18 and causes the flow sensitive valve 102 to be operated to a position blocking motor chamber 56 from and connecting motor chamber 58 to the port 74 of the valve :18, the latter port of which is now connected to the tank. The control handle 71 of the valve 16 will return to the neutral motor stop position after the main piston 36 of the motor comes into abutment with the auxiliary piston 38. To adjust the plowing depth the control-handle 71 of the valve 16 is operated to the L- l or R-l position and at low flow the flow sensitive 'valve member 102 remains in the centered position shown.

The invention thus provides an efiicient, low-cost hydraulic system for remotely controlling the operation of a load device. The length of stroke of the main motor may be adjusted in'one direction of operation and the directional operation of the motor may also be controlled from for example, a tractor seat, by the operation of only one control lever. This is of importance in plowing operations when at the end of a now being plowed the tractor is turned around at which time the plow must be raised and speedily returned to its former plowing depth to start a plowing operation in the opposite direction. The operator of the system need only operate one control lever to the raise and then to the lowering position and when the plow reaches the adjusted preselected plowing depth and motor-will stop and the control handle of the directional valve is automatically released to the neutral position I a It should also be noted that the pressure fluid source and manually operated control is located at one station and only two plumbing lines are necessary for connecting this station to the remotely located station having the actuator for the load device and the stroke limiting device or stop member for adjusting the stroke of the actuator. Thus, only a single manually operated control is utilized for controlling the operation of both the actuator andthe stroke limiting member and only two, dual function, supply and return conduits arenecessary for connecting one station, located on the tractor for example, to the remote station located, for example, on the trailing implement being towed by the tractor.

While the form of-embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A flow sensitive directional valve comprising a body having a valve member shiftably mounted therein including opposed operating surfaces and forming operating chambers for the surfaces, the body having a pair of external connection ports separately connected to the chambers and a third external connection port leading to the valve and blocked thereby from the pair of ports in the neutral position of the valve and interconnected to one of the pair of ports when the valve is operated to either side of the neutral position, a flow passage in the valve member and a flow passage in the body interconnected to each other for interconnecting the pair of ports to each other in the neutral position of the valve, means' closing communication between said flow passages to close communication between the pair of ports when the valve member is shifted to either side of the neutral position, resilient means biasing the valve to the neutral position, and'flow sensing means in one of the said flow passages responsive to predetermined flow rates between the ports in either direction of operation for creating a ditferentialpressure on the operating surfaces of the valve to shift said valve from the neutral position.

2. A flow sensitive directional valve comprising a body having a valve member shiftably mounted therein including opposed operating surfaces and forming operating chambers for the surfaces, the body having a pair of external connection ports separately connected to the chambers and a third external connection port leading to the valveand blocked thereby from the pair of ports in the neutral position of the valve and interconnected to one of the pair of'ports when the valve is operated to either side of the neutral position, a flow passage in the valve member and a flow passage in the body interconnected to'each other for interconnecting the pair of ports to each other in the neutral position of the valve, means closing communication between said flow passages when the valve member is shifted to either side of neutral position, resilient means biasing thevalve to the neutral position, flow sensing means in one of the said flow passages responsive to predetermined flow rates between the ports in either direction of operation for creating adiiferential pressure on the operating surfaces of the valve to shift said valve from'the neutral position, and a normally closed venting valve in the valve member flow passage operable to the open position to interconnect the chambers to each other when flow to one of the external connection ports ceases for returning the valve to the neutral position.

3. A flow sensitive directional valve comprising a body having avalve member shiftably. mounted therein including opposed operating surfaces and forming operating chambers for the surfaces, the body having a pair of external connection ports separately connected to the chambers and a third external connection port leading to the valve and blocked thereby from the pair of ports in the neutral position of the valve and interconnected to one a of the pair of ports when the valve is operated to either side of the neutral position, aflow passage in the valve member and a flow passage in the body interconnected to g each other for interconnecting the pair of ports to each 1-2 when flow to one of the external. connection ports ceases for returning thevalve 'to the neutral position.

4. Allow sensitive'directional valve comprising a-body having avalve member therein including opposed'operating' surfaces, the body having'three external connection ports leading to the valvemember two of'which are separately continously connected to the operating surfaces, a flow passage in the valve member and a flow passage in flow passage in the valve member and a flow passage in the body interconnected to each other'for connecting one of the two external connection ports to the other of said two ports in the neutral position of the valve, said flow passages being closed from communication with each other when said'valve member is shifted to opposite sides of the neutral position, resilient means biasing the valve member to the'neutral position blocking the other of said two ports from the third port, a flow sensing means in the valve member flow passage responsive to predetermined flow rates in said passage between the said two ports in either direction for creating a differential'pressure on the operating surfacesof the valve member to shift said'member fromthe neutral position for connecting the'said other of two' ports tothe third port, valve means in the body opening toflow from the third port to the other of said ports, and resilient meansbiasing the valve means to the closed position of greater resistance than the resistance of the valve member resilient biasing means.

5. A flow sensitive directional-valve comprising a body having a valve member therein including opposed operating surfaces, the body having three external connectionports leading-to the valve member two of which are separately continuously connected to the operating surfaces, a flowpassage in the valve member and a flow passage in the body connecting one of the two external connection" portsto the other of said two ports in the neutral position of the valve, said flow'passages being closed from communication with each other when the valve member is shifted to either side of neutral position,- resilient means biasing the valve member to the neutral position blocking both of said two ports from the third port, a flow sensing means in the valve member flow References Cited in the file of this patent UNITED STATES PATENTS 2,737,196 *Eames Mar. 6, 1956 

